Thermostatic spring.



No. 857,709. PATENTED JUNE 25, 1907.

T. H. WURMB 6: R. BAUMANN.

THERMOSTATIG SPRING.

APPLICATION FILED nno.11.19oe.

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THEODORE H. WURMB AND ROBERT .BAUMANN, or sr; Louis, Mrssoinu.

THERMOSTATBG SFFZBNGG To all whom it may concern:

Be it known that we, THEODORE H. .WURMB and ROBERT BAUMANN,CitiZ8I1S of the United ,States, and residents of St. Louis, Missouri,

have invented'certain new and useful Improvements in Thermostatic Springs, of which the following is a specification containing a yfull, clear, and exact description, reference be-v ing had to the accompanying drawings, forming a part hereof.

Our invention relates to thermostatic springs, and is an improvement on a similar device shown in our Patent No. 770,345, issued September 20, 190 1.

' In the patent above referred to, the curved metallic strips forming the. spring were wound with a fiat strip, or ribbon, of metal and considerable space was left between the convolutions of said strip, which arrangement materially lessened the sensitiveness of. the spring, and which defect is remedied by winding the spring with a wire so as to entirely cover the same, as shown in the present application which arrangement produces-a very sensitive spring. v,

Our present invention relates particularly to a thermostatic spring which. is particularly adapted for use in fire alarm devices, and in self-recording thermometers for use in indicating abnormally high temperatures, for insimilar purposes.

While the spring herein shown and described is particularly adapted for use in devicesrecording abnormally high temperatures, it can be readily used in thermometers which indicate and record natural or normal temperatures. Where the spring is used in a fire or temperature alarm, certain mechanism is actuated by said spring to close an electric circuit or give an alarm when the temperature rises or lowers to the degree of temperature on the dial 0 the alarm device.

To the above pur oses, our invention consists in certain nove features of construction and arrangement of parts, which will be hereinafter more, fully set forth, pointed out in the claims, and illustrated in the accompanying drawings, in which:

Figure lis an interior view of the housing of 'a'fire alarm device in which our improved Specification of'Letters Patent. Application filed December 11,1906. fierial Nd. 3 27.379. I

stance, in dry kilns, bake ovens, and other,

' the edges of the strips 1 and 2 are curved correspondin to the set position of a pointer Patented. June 25, 1907,

Fig. 4 is a crosssection of the spring, and showing the winding thereon.

Referring by numerals to the accompanying drawings:1 designates the outer member of the spring, which is preferably con structed of a thin fiat strip of steel, semi-circular in form, and placed immediately against the inner face of this strip 1 is a strip 2, which issimilar in form and size to said strip 1 ,"and said inner strip or liner being formed of German silver, or analogous material. Bearings 3 and l are rigidly fixed to the ends of the springs so formed'by means of rivets 4 or analogous fastening devices which pass through coinciding'apertures formed in the ends of the strips of the spring and through said bearings, and by means of these bearin s the spring is arranged for operation in the t ermometer or fire alarm housing.

5 designates a wire of German sliver, or analogous material, which is wound upon the semi-circular spring formed by the strips 1 and-2, and the last one or two coils at each end of said wire are soldered to the to and bottom edges of the strips so as to rigi ly secure the ends of the wire, and also to assist in uniting the ends of the strips 1 and 2. The Wire 5 is wound upon the strips with a certain amount of tension, and, when in positi on, firmly presses the ed es of the strips together, and the portions o fisaid wire between It is preferable that the strip 2 and wire 5 9 3 be formed of the same material, and where German silver is-rnade use of, the strip 2 can be cold rolled, or drawn; and by so doin 7 said strip becomes materially hardened. The stri ferent a oys with zinc as the basis of the composition, and it is essential that the mate rial of which the strip 2 is formed be cold rolled or hardened, and the wire drawn to a certain hardness so that when the latter is 105 wound on the two strips it will curve properly over the sides thereof.

in the drawings we have shownf our im- 1 proved spring as being applied. to the housing of a fire alarm device, with the double bear- 1' 1o and wire may be formed of dif- 10o mg 3 loosely mounted upon a post 7, and with the single bearing 4 pivotally connected to a swinging arm This arm 8 bears upon an insulated pin 9 carried by a segment 10, which segment meshes with the teeth of the pinion 11, and the shaft of said pinion carries a pointer 12. The housing of the device may be perforated, or entirely closed and (lust proof, as desired.

when the device as shown is set for operation, the pointer 12 is moved upon the dial to the point corresponding to the degree of temperature at which the alarm is given, and this action moves the insulated pin 9 away from the arm 8. When the temperature rises to the degree at which. the pointer is set on the dial, the thermostatic spring expands, shifting the arm around so that the free end thereof contacts with the pin 9, thus closing the circuit and sounding the alarm. When the temperature lowers, the spring will correspondingly contract, and the mechanical parts of the device are returned to their normal positions. Our improved form of spring is very sensitive to changes of temperature and uniformly expands and contracts, and will maintain its position continuously at any fixed degree of temperature within the compass of the instrument in which it is used.

The strips forming, the spring are made and the winding of the wire is done by spe, cial machinery, thereby reducing the cost and insuring uniformity in size of said springs; and the completed springs are adapted for use at any point where an extremely accurate, sensitive spring is required, and particularly for use in thermo-mstruments wherein abnormal temperatures are indicated and recorded.

We claim l. A. thermostatic spring, comprising two similarly curved strips, one of spring steel and the other of cold rolled German silver, and a German. silver Wire closely wound upon said strips, in such a manner as to entirely inclose the main body portions of the curved strips.

2. A thermostatic spring, comprising two similarly curved strips, one of spring steel and the other of cold rolled German silver, a German silver wire closely wound upon said strips in such a manner as to entirely inclose the main body portions of the curved strips, the ends of which strips are rigidly united,

and the ends of the wire being united to the strips.

3. A thermostatic spring, comprised of two similarly curved strips, the outer one of which is formed of spring steel, the inner one being formed of zinc, alloyed with nickel, copper, and antimony, and which strips are tightly wound with a wire formed of the same material as the second strip, in such a manner as to entirely inclose the main body portions of the curved strips.

4. A thermostatic spring, two similarly curved strips, spring steel, the inner one of German silver, the edges of the ends of said springs being united. by solder, and a'wire of German silver closely wound upon said strips in such a manner as to entirely inclose the main body portions of the curved strips, and the ends of said wire being united with the ends of the strips.

5. A thermostatic spring, composed of two similarly curved'strips, the outer one of spring steel, the inner one of German silver, and a German silver wire wound upon said strips in such a manner as to form air spaces between the outer faces of the pair of strips and the corresponding portions of the wire.

6. A thermostatic spring, composed of two similarly curved strips, the outer one of spring steel, the inner one of alloy, and a wire tightly wound upon said strips so as to entirely inclose the main body portions of the strips, which wire and the inner'strip are formed of an alloy having zinc as the basis of its composition. 1

In testimony whereof, we have signed our names to this specification, in presence of two subscribing witnesses.

THEODORE H. WURMB. ROBERT BAUMANN. Nitnesses:

M. P. SMITH, E. L. WALLAeE.

composed of theouter one of 

